Short Answer 
To enhance a video on your iPhone, first open the Photos app and select the video you wish to edit. Then, tap the “Edit” button to access various editing tools, where you can adjust video quality by trimming, and modifying exposure, brightness, and contrast settings.
Step 1: Open the Photos App
Begin by locating and launching the Photos app on your iPhone. Navigate through your gallery and find the video you want to enhance. Tap on it to view the video details and prepare for editing.
Step 2: Access the Editing Tools
Once you have your video open, look for the “Edit” button in the top-right corner of the screen. Tapping this button will activate a range of editing tools designed to help you improve the video’s appearance directly on your device.
Step 3: Adjust Video Quality
Within the editing interface, you have several options to enhance your video quality. Consider the following adjustments:
- Use the trimming handles to change the video’s length.
- Tap on the “Settings” icon to access various options.
- Adjust settings like exposure, brightness, and contrast to optimize your video.